University of Zurich, Heidelberg University
89 papers in the library · 11,879 citations · publishing 1998-2026
bioRxiv Preprint Server November 1, 2022 Flora Moujaes, Jie Lisa Ji, Masih Rahmati et al. 4 citations preprint
Ketamine is a promising therapy for treatment-resistant depression, but why some people respond better than others remains unclear. The molecular mechanisms of ketamine are not yet connected to its effects on brain activity and behavior.
medRxiv September 9, 2022 Devon Stoliker, Leonardo Novelli, Franz X. Vollenweider et al. 4 citations preprint
Psilocybin reduces the brain's top-down control from resting state networks to the amygdala, which is involved in emotion appraisal and regulation. In a randomized, double-blind, placebo-controlled trial of 24 healthy adults given 0.215 mg/kg psilocybin, effective connectivity decreased from the default mode network and salience network to the amygdala, and within the DMN and SN, while connectivity within the central executive network increased. These changes were linked to altered emotion and meaning under the drug, suggesting that attenuation of the amygdala signal may serve as a biomarker for psilocybin's therapeutic effects in conditions like addiction and depression.
Journal of Vision March 19, 2010 O. Carter, John D. Pettigrew, Felix Hasler et al. 3 citations
Binocular rivalry, the fluctuation in visual awareness when different images are shown to each eye, is slowed by the hallucinogenic compound psilocybin, the active ingredient in magic mushrooms. In ten healthy human subjects, psilocybin reduced the rate of switching between percepts and increased the experience of mixed or transitional percepts. Pretreatment with ketanserin, a selective 5-HT2A receptor antagonist, blocked most of psilocybin's positive psychotic-like symptoms but did not affect the slowing of binocular rivalry switching or negative symptoms related to reduced arousal and vigilance. This suggests that the slowing of binocular rivalry by psilocybin is not mediated by 5-HT2A receptors but may instead involve 5-HT1A receptor activation reducing serotonin release from the brainstem raphe nuclei, linking rivalry switching rate to arousal and attention.
Therapeutische Umschau June 1, 2003 Franz X. Vollenweider, M. F. I. Vollenweider-Scherpenhuyzen 3 citations
MDMA and its analogues are amphetamine derivatives that produce an altered emotional state. For over a decade, ecstasy has been the second most common recreational drug among young adults, especially in the techno scene, after cannabis. A recent survey indicates a shift toward classic amphetamine and hallucinogen use, possibly due to concerns about ecstasy's neurotoxicity and somatic risks. Among hallucinogens, psilocybin mushrooms and LSD are most used. This review summarizes the psychological and somatic effects of hallucinogens, amphetamines, and entactogens.
bioRxiv Preprint Server January 28, 2019 Thomas Pokorny, Patricia Duerler, Erich Seifritz et al. 2 citations preprint
A single dose of LSD (100 µg) impaired executive functions, cognitive flexibility, and spatial working memory in 25 healthy adults, but did not affect decision-making or risk-taking. These cognitive deficits were blocked by pretreatment with the 5-HT2A antagonist ketanserin (40 mg), indicating that the serotonin 2A receptor system is involved in specific cognitive processes. The findings suggest that blocking this receptor might help improve cognitive dysfunctions seen in psychiatric disorders.
Molecular Psychiatry April 8, 2026 Johannes G. Ramaekers, Kim P. C. Kuypers, Franz X. Vollenweider 1 citation
MDMA, originally developed for military purposes and later used recreationally, is now being tested in clinical trials for PTSD. A narrative review of placebo-controlled single-dose studies in healthy volunteers found that 75-125 mg of MDMA acutely enhances mood, empathy, trust, and arousal while transiently impairing memory encoding through increased serotonin signaling. Motor coordination and cognitive flexibility decline modestly, but inhibitory control and executive function remain largely intact. Post-acutely, fatigue and low mood may occur. These effects may support trauma processing by facilitating fear extinction and disrupting negative memory reconsolidation, though they also complicate trial design by compromising blinding and inflating expectancy.
Psychopharmacology November 5, 2025 Milad Soltanzadeh, Wang Zheng, Shona G. Allohverdi et al. 1 citation
Ketamine and psilocybin, two drugs with therapeutic potential for depression, produce distinct effects on brain electrical activity. Ketamine disrupts the balance between excitation and inhibition in neural circuits, as shown by changes in the aperiodic components of EEG spectra, and reduces beta band activity. Psilocybin also reduces alpha power in similar brain regions but does not affect beta activity or aperiodic components in the same way. These differences reflect their different mechanisms: ketamine blocks NMDA receptors while psilocybin targets serotonin receptors. Ketamine's unique EEG signature supports its role as a model for prodromal psychosis.
iScience May 19, 2024 Andres Ort, John W Smallridge, Erich Seifritz et al. 1 citation
Psilocybin, a serotonergic psychedelic being studied for psychiatric treatment, preserved reinforcement learning in a probabilistic cue-reward task using emotional faces presented consciously or subconsciously. Across dosages, psilocybin was statistically noninferior to placebo and suggested higher exploratory behavior. The 20 mg group showed significantly better learning rates than placebo. Psilocybin led to inferior learning with subconscious cues compared to placebo, but better results with conscious neutral cues in some conditions. The findings indicate that modulating serotonin signaling with psilocybin sufficiently preserves reinforcement learning.
bioRxiv (Cold Spring Harbor Laboratory) November 7, 2025 Gabrielle Allohverdi, Milad Soltanzadeh, André Schmidt et al. preprint
Ketamine and psilocybin, two hallucinogenic compounds being explored as treatments for major depressive disorder, affect sensory learning in the brain differently. By combining computational modeling with electroencephalography (EEG) data from a prior experiment, researchers analyzed how these drugs alter the brain's processing of unexpected sounds during an auditory task. Ketamine produced a larger reduction in the influence of sensory precision between 207 and 316 milliseconds after a sound, peaking at 277 milliseconds in frontal central brain regions, while psilocybin showed no significant effect in that measure. Both drugs reduced the expression of belief precision between 160 and 184 milliseconds, peaking at 172 milliseconds.
July 18, 2025 Marvin M. Urban, Eric Zillich, Nathalie M. Rieser et al. preprint
A single dose of psilocybin (25 mg) was associated with changes in DNA methylation in patients with alcohol use disorder. One methylation site in the TLE4 gene and a region in the RASGRP4 gene showed significant alterations. Co-methylation networks linked to psilocybin treatment were also associated with reduced depressive symptoms and drinking behavior, and involved genes related to neuroplasticity and immune function. Baseline methylation differences between treatment responders and non-responders appeared in genes related to synaptic plasticity and neurotransmitter systems. The findings are preliminary due to the small sample size but align with prior research and suggest possible biological pathways for psilocybin's therapeutic effects.
Research Square September 26, 2024 Shona G. Allohverdi, Milad Soltanzadeh, André Schmidt et al.
Ketamine and psilocybin affect sensory learning in the brain through different neural mechanisms. By combining computational modeling with EEG data from a previous study, researchers analyzed how these drugs alter the brain's processing of prediction errors during an auditory task. Ketamine produced a larger reduction in sensory precision from 207 to 316 milliseconds after sounds, peaking at 277 milliseconds in frontal central brain regions, while psilocybin showed no significant effect on this measure. Both drugs reduced belief precision between 160 to 184 milliseconds, peaking at 172 milliseconds. For higher-level volatility prediction errors, ketamine reduced expression while psilocybin had no effect at 312 milliseconds. These distinct effects could inform tailored therapies for major depressive disorder.
Scientific Reports April 23, 2024 Berit Singer, Daniel Meling, Matthias Hirsch-Hoffmann et al.
No Summary
Nervenheilkunde April 1, 2024 Eva Maria Schindowski, Franz X. Vollenweider
The article presents two treatment courses of patients with recurrent depression who were treated with psilocybin. Worldwide, the number of studies examining the use of psilocybin for depression is steadily growing, increasing interest in this therapy. While some researchers note a current 'hype' around psychedelics, patients and their accompanying clinicians have very different experiences with the substance. There are few detailed descriptions of long-term courses that allow outsiders deeper insight. The case examples show both the enormous potential of psilocybin to positively influence depressed patients' lives and that some patients, even with repeated use, do not experience long-term benefit.
Psychopharmacology July 1, 2017 Rainer Kraehenmann, Dan Pokorný, Leonie Vollenweider et al.
Lysergic acid diethylamide (LSD) produces waking mental imagery that resembles dreaming, an effect driven by activation of the 5-HT2A receptor. In a study with 25 healthy subjects, LSD (100 mcg orally) significantly increased cognitive bizarreness in guided mental imagery reports compared with placebo, and this increase correlated with a loss of self-boundaries and cognitive control. Both the imagery changes and altered state of consciousness were fully blocked by the 5-HT2A antagonist ketanserin (40 mg orally). The findings suggest that LSD-induced dreamlike imagery depends specifically on 5-HT2A receptor activation.